It is known in the prior art to provide amplifier circuits having gain control, which amplify complex ac signals to a level determined by a dc control voltage. So long as the dc voltage varies over a relatively small range of values, such systems may be quite simple. However, for wide ranges of gain, non-linearities appear because the responses of transistors are not linear, but are anti-logarithmic. To compensate for the anti-logarithmic responses of transistors, the ac signals has been heretofore applied to the transistors via circuitry which has a logarithmic response (see Blackmer U.S. Pat. No. 3,714,462). The present invention represents an improvement in circuitry of the latter type.